The 20-year-old American actress and singer has suffered from bulimia, self-harming and depression in the past, and told Cosmo On Campus it might have been better to wait a while after tackling her problems, before she jumped back in to work.

Demi, who joined the show as a judge in the autumn of 2012, said: "I don't think I was ready when I started on The X Factor. In an ideal situation, I would have maybe waited a year or more [after coming out of treatment]."

But the star revealed everything worked out for the best.

"I dived into work really quickly and maybe that wasn't the best idea at the time," she said. "But the place I am in today is so much better than I could have ever imagined, so I'm really glad."

Demi also opened up about battling bulimia, saying she wished she had had someone in the public eye to relate to when she was struggling with the eating disorder.

She explained: "I was about 12 or 13 when I developed my eating disorder, and at that time nobody in the public eye talked about their body issues.

"I feel that if someone had admitted they had a problem, then I wouldn't have gone down that route myself.

"That's my goal in talking about my problems. I want to be the person for other girls that I needed to admire when I was looking for help and strength. It's okay to love your body the way it is and it's okay to reach out for help if you have drug and alcohol problems, or if you're self-harming or being bullied."